All Articles from Erich Götzinger -Optical Coherence Tomography News

Articles from Erich Götzinger

1-24 of 56 1 2 3 »
1. Spectral degree of polarization uniformity for polarization-sensitive OCT
  
  Explore Taylor & Francis Online Dec 23 2015
  
  Depolarization of light can be measured by polarization-sensitive optical coherence tomography (PS-OCT) and has been used to improve tissue discrimination as well as segmentation of pigmented structures. Most approaches to depolarization assessment for PS-OCT – such as the degree of polarization uniformity (DOPU) – rely on measuring the uniformity of polarization states using spatial evaluation kernels. In this article, we present a different approach which exploits the spectral dimension. We introduce the spectral DOPU for the pixelwise analysis of polarization state variations between sub-bands of the broadband light source spectrum. Alongside a comparison with conventional spatial and temporal DOPU algorithms, we demonstrate ...
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  Mentions: Medical University of Vienna
2. Polarisation-sensitive OCT is useful for evaluating retinal pigment epithelial lesions in patients with neovascular AMD
  
  Explore BJO Online Jul 16 2015 Ophthalmology
  
  Background/aims To examine the reproducibility of lesion dimensions of the retinal pigment epithelium (RPE) in neovascular age-related macular degeneration (AMD) with polarisation-sensitive optical coherence tomography (PS-OCT), specifically imaging the RPE. Methods Twenty-six patients (28 eyes) with neovascular AMD were included in this study, and examined by a PS-OCT prototype. Each patient was scanned five times at a 1-day visit. The PS-OCT B-scan located closest to the macular centre presenting with RPE atrophy was identified, and the longitudinal diameter of the lesion was quantified manually using AutoCAD 2008. This procedure was followed for the identical B-scan position in all five ...
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  Mentions: Medical University of Vienna
3. Peripapillary rat sclera investigated in vivo with polarization sensitive optical coherence tomography
  
  Explore iovs.org Oct 31 2014 Ophthalmology
  
  Purpose: To demonstrate polarization sensitive (PS) optical coherence tomography (OCT) for non-invasive, volumetric, and quantitative imaging of the birefringent properties of the peripapillary rat sclera. To compare the findings in PS-OCT images to state-of-the-art histomorphometric analysis of the same tissues. Methods: A high-speed PS-OCT prototype operating at 840 nm was modified for imaging the rat eye. Densely sampled PS-OCT raster scans covering an area of ~1.5 mm × 1.5 mm centered at the papilla were acquired in the eyes of anesthetized, male Sprague Dawley rats. Cross-sectional PS-OCT images were computed and fundus maps displaying the birefringent properties of the ...
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  Mentions: Medical University of Vienna University of Vienna
4. Imaging Retinal Pigment Epithelial Proliferation Secondary to PASCAL Photocoagulation In Vivo by Polarization-sensitive Optical Coherence Tomography
  
  Explore ScienceDirect Mar 2 2013 Ophthalmology
  
  Purpose To image the retinal pigment epithelium (RPE) after macular laser and to monitor healing responses over time in vivo in patients with diabetic maculopathy using polarization-sensitive optical coherence tomography (OCT). Design Prospective, nonrandomized clinical trial. Methods In this single-center trial (Department of Ophthalmology and Optometry, Medical University of Vienna, Vienna, Austria), 13 patients (13 eyes) underwent grid photocoagulation for diabetic maculopathy. Retinal healing processes were continuously followed over the course of 3 months. A polarization-sensitive OCT prototype was used, allowing detection and measurement of the RPE changes based on their specific polarization-scrambling qualities. Results After 1 day, the intraretinal ...
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  Mentions: Medical University of Vienna
5. Retinal polarization-sensitive optical coherence tomography at 1060 nm with 350 kHz A-scan rate using an Fourier domain mode locked laser
  
  Explore SPIE | Journal Feb 5 2013 Ophthalmology
  
  We present a novel, high-speed, polarization-sensitive, optical coherence tomography set-up for retinal imaging operating at a central wavelength of 1060 nm which was tested for in vivo imaging in healthy human volunteers. We use the system in combination with a Fourier domain mode locked laser with active spectral shaping which enables the use of forward and backward sweep in order to double the imaging speed without a buffering stage. With this approach and with a custom designed data acquisition system, we show polarization-sensitive imaging with an A-scan rate of 350 kHz. The acquired three-dimensional data sets of healthy human volunteers ...
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  Mentions: Medical University of Vienna Technical University of Denmark (DTU) Ludwig Maximilian University of Munich
6. Measuring Retinal Nerve Fiber Layer Birefringence, Retardation, and Thickness Using Wide-Field, High-Speed Polarization Sensitive Spectral Domain OCT
  
  Explore iovs.org Jan 8 2013 Ophthalmology
  
  Purpose. We presented a novel polarization sensitive optical coherence tomography (PS-OCT) system for measuring retinal nerve fiber layer (RNFL) birefringence, retardation, and thickness, and report on the repeatability of acquiring these quantities. Methods. A new PS-OCT system, measuring at 840 nm, was developed that supports scan angles of up to 40° × 40° with an A-scan rate of 70 kHz. To test the performance and reproducibility, we measured 10 eyes of 5 healthy human volunteers five times each. All volunteers were imaged further with scanning laser polarimetry (SLP). The obtained RNFL birefringence, retardation, and thickness maps were averaged, and standard deviation ...
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  Mentions: Medical University of Vienna Canon Medical Systems
7. Lesion Size Detection in Geographic Atrophy by Polarization-sensitive Optical Coherence Tomography and Correlation to Conventional Imaging Techniques
  
  Explore iovs.org Dec 20 2012 Ophthalmology
  
  Purpose: To investigate the reproducibility of automated lesion size detection in patients with geographic atrophy (GA) using polarization-sensitive spectral domain-OCT (PS-OCT) and to compare findings with scanning laser ophthalmoscopy (SLO), fundus autofluorescence (FAF), and intensity based SD-OCT. Methods: 29 eyes of 22 patients with GA were examined by PS-OCT, selectively identifying the retinal pigment epithelium (RPE). A novel segmentation algorithm was applied, automatically detecting and quantifying areas of RPE atrophy. The reproducibility of the algorithm was assessed and lesion sizes were correlated with manually delineated SLO, FAF and intensity based SD-OCT images to validate the clinical applicability of PS-OCT in ...
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  Mentions: Medical University of Vienna
8. High-speed polarization sensitive optical coherence tomography scan engine based on Fourier domain mode locked laser
  
  Explore opticsinfobase.org Oct 30 2012
  
  We report on a new swept source polarization sensitive optical coherence tomography scan engine that is based on polarization maintaining (PM) fiber technology. The light source is a Fourier domain mode locked laser with a PM cavity that operates in the 1300 nm wavelength regime. It is equipped with a PM buffer stage that doubles the fundamental sweep frequency of 54.5 kHz. The fiberization allows coupling of the scan engine to different delivery probes. In a first demonstration, we use the system for imaging human skin at an A-scan rate of 109 kHz. The system illuminates the sample with ...
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  Mentions: Medical University of Vienna Ludwig-Maximilians University
9. Large-field high-speed polarization sensitive spectral domain OCT and its applications in ophthalmology
  
  Explore opticsinfobase.org Oct 9 2012 Ophthalmology
  
  We present a novel spectral domain polarization sensitive OCT system (PS-OCT) that operates at an A-scan rate of 70 kHz and supports scan angles of up to 40° × 40°. The high-speed imaging allows the acquisition of up to 1024 × 250 A-scans per 3D scan, which, together with the large field of view, considerably increases the informative value of the images. To demonstrate the excellent performance of the new PS-OCT system, we imaged several healthy volunteers and patients with various diseases such as glaucoma, AMD, Stargardt’s disease, and albinism. The results are compared with clinically established methods such as scanning ...
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  Mentions: Medical University of Vienna Canon Medical Systems
10. Polarization sensitive optical coherence tomography of melanin provides intrinsic contrast based on depolarization
  
  Explore opticsinfobase.org Jun 21 2012 Dermatology
  
  Polarization sensitive optical coherence tomography (PS-OCT) is a functional extension of OCT. In addition to imaging based on tissue reflectivity, PS-OCT also enables depth-resolved mapping of sample polarization properties such as phase-retardation, birefringent axis orientation, Stokes vectors, and degree of polarization uniformity (DOPU). In this study, PS-OCT was used to investigate the polarization properties of melanin. In-vitro measurements in samples with varying melanin concentrations revealed polarization scrambling, i.e. depolarization of backscattered light. Polarization scrambling in the PS-OCT images was more pronounced for higher melanin concentrations and correlated with the concentration of the melanin granules in the phantoms. Moreover, in-vivo ...
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  Mentions: Medical University of Vienna University of Vienna
11. High-speed polarization-sensitive OCT at 1060 nm using a Fourier domain mode-locked swept source
  
  Explore Linking to Scitation Content May 3 2012 Ophthalmology , Tunable Sources
  
  Optical coherence tomography (OCT) in the 1060nm range is interesting for in vivo imaging of the human posterior eye segment (retina, choroid, sclera), as it permits a long penetration depth. Complementary to structural images, polarization-sensitive OCT (PS-OCT) images visualize birefringent, polarization-maintaining or depolarizing areas within the sample. This information can be used to distinguish retinal layers and structures with different polarization properties. High imaging speed is crucial for imaging ocular structures in vivo in order to minimize motion artifacts while acquiring sufficiently large datasets. Here, we demonstrate PS-OCT imaging at 350 kHz A-scan rate using a two-channel PS-OCT system in ...
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  Mentions: Medical University of Vienna Technical University of Denmark (DTU) Ludwig Maximilian University of Munich
12. Feature Of The Week 4/29/12: Medical University of Vienna Demonstrates Automated Measurement of Choroidal Thickness in the Human Eye by PS-OCT
  
  Explore Optical Coherence Tomography News Apr 29 2012 Ophthalmology
  
  Researchers at the Medical University of Vienna have a long history of outstanding contributions to the field of Optical Coherence Tomography dating back 25 years. This week work by Dr. Hitzenberger, one of the pioneers of the field, and his colleagues is featured demonstrating automated measurement of choroidal thickness in the human eye by polarization sensitive optical coherence tomography. Below is a summary of their work.Imaging of retinal layers and quantitative measurements of their thickness are among the most important applications of OCT. E.g., the total retinal thickness is an important quantity for diagnosis of diabetic retinopathy, the ...
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  Mentions: Medical University of Vienna
13. High-Speed Retinal Imaging with Polarization-Sensitive OCT at 1040 nm
  
  Explore LWW Online Apr 26 2012 Ophthalmology
  
  Purpose. To demonstrate the ability of a new high-speed polarization-sensitive optical coherence tomography (PS-OCT) system for retinal imaging at 1040 nm. Methods. A new polarization-sensitive swept source OCT system in the 1 [mu]m wavelength range is used to image the retina of healthy volunteers. The instrument is operated at an A-scan rate of 100 kHz which is about three times faster than previously reported PS-OCT instruments in this wavelength region. The increased imaging speed can be used to record densely sampled volumes of the retina. Moreover, it enables averaging of several B-scans recorded at the same location to obtain ...
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  Mentions: Medical University of Vienna
14. Automated measurement of choroidal thickness in the human eye by polarization sensitive optical coherence tomography
  
  Explore opticsinfobase.org Mar 19 2012 Ophthalmology
  
  We present a new method to automatically segment the thickness of the choroid in the human eye by polarization sensitive optical coherence tomography (PS-OCT). A swept source PS-OCT instrument operating at a center wavelength of 1040 nm is used. The segmentation method is based entirely on intrinsic, tissue specific polarization contrast mechanisms. In a first step, the anterior boundary of the choroid, the retinal pigment epithelium, is segmented based on depolarization. In a second step, the choroid-sclera interface is found by using the birefringence of the sclera. The method is demonstrated in five healthy eyes. The mean repeatability (standard deviation ...
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  Mentions: Medical University of Vienna
15. Morphologic Characteristics of Idiopathic Juxtafoveal Telangiectasia Using Spectral-Domain and Polarization-Sensitive Optical Coherence Tomography
  
  Explore LWW Online Dec 27 2011 Ophthalmology
  
  Purpose: Idiopathic juxtafoveal telangiectasia (IJT) is characteristically associated with pigmentary changes. Polarization-sensitive spectral-domain optical coherence tomography (PS-SD-OCT) enables imaging of the retinal pigment epithelium (RPE) and similar melanin-containing structures based on specific polarization properties. This study examined IJT with the latest-generation SD-OCT and PS-SD-OCT, identifying pathophysiologically relevant characteristics of the retinal layers and RPE. Methods: Twenty-two eyes of 12 patients with IJT were examined by PS-SD-OCT, with special focus on RPE detection and segmentation. Furthermore, SD-OCT technology (Cirrus, Spectralis, and 3D-OCT-1000) was applied. Characteristics of the retinal layers and RPE were evaluated. A classification system based on OCT characteristics of ...
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  Mentions: Medical University of Vienna
16. Speckle noise reduction in high speed polarization sensitive spectral domain optical coherence tomography
  
  Explore opticsinfobase.org Jul 14 2011 Ophthalmology
  
  We present a high speed polarization sensitive spectral domain optical coherence tomography system based on polarization maintaining fibers and two high speed CMOS line scan cameras capable of retinal imaging with up to 128 k A-lines/s. This high imaging speed strongly reduces motion artifacts and therefore averaging of several B-scans is possible, which strongly reduces speckle noise and improves image quality. We present several methods for averaging retardation and optic axis orientation, the best one providing a 5 fold noise reduction. Furthermore, a novel scheme of calculating images of degree of polarization uniformity is presented. We quantitatively compare the ...
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  Mentions: Medical University of Vienna
17. Speckle noise reduction by averaging in polarization sensitive spectral domain optical coherence tomography
  
  Explore SPIE Digital Library Jun 6 2011 Ophthalmology
  
  We demonstrate an ultra high speed fiber based polarization sensitive spectral domain optical coherence tomography system, using two ultra high speed CMOS line scan cameras. With this system an A-scan rate of up to 128 kHz was achieved. The system is based on polarization maintaining fibers and retrieves the backscattered intensity, retardation and optic axis orientation with only one A-scan per measurement location. This high speed data acquisition enables averaging of several acquired B-scans of intensity, retardation, optic axis orientation, and Stokes vectors, which strongly reduces speckle noise. We discuss different averaging techniques and compare the results in healthy human ...
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  Mentions: Medical University of Vienna
18. In vivo observation of human retinal-cone outer-segment renewal
  
  Explore Home: SPIE.org Feb 23 2011 Ophthalmology
  
  Cone-disk shedding and generation can be observed using transverse-scanning optical coherence tomography and scanning-laser ophthalmoscopy. Vision is one of the most complex human senses. The eye projects images from our environment onto the retina, which consists of a variety of different cells. The retina preprocesses this information before sending it to the brain as electrical signals. Many different retinal diseases—such as age-related macular degeneration—distort the fragile retinal structure, leading to (for example) reduced visual perception and eventual blindness. Maintenance of a healthy retina requires interactions between its photosensitive cells and the retinal-pigment epithelium (RPE). There are two different ...
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  Mentions: Medical University of Vienna
19. Ultra-high-speed polarization sensitive OCT in the human retina using a single spectrometer
  
  Explore SPIE Digital Library Feb 10 2011 Ophthalmology
  
  We present a single spectrometer functional spectral domain optical coherence tomography system, which allows for encoding additional information within the spatial frequencies. The method is based on a differentiation between orthogonal polarization channels through spatial modulation introduced by an electro-optic modulator. This method is used to perform Ultrahigh- speed retinal polarization sensitive optical coherence tomography (PSOCT). With this setup, we realized for the first time polarization sensitive OCT measurements of the human retina in-vivo, with camera line rates of up to 160.000 A-scans per second. Compared to PSOCT systems, operating at traditional line rates, this significantly improves patient comfort ...
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  Mentions: Medical University of Vienna Femtolasers
20. Spectral domain polarization sensitive optical coherence tomography at 1.55 μm: novel developments and applications for dynamic studies in materials science
  
  Explore SPIE Digital Library Feb 10 2011 NDE/NDT
  
  In this paper it is demonstrated, how research in optical coherence tomography (OCT) for biomedical diagnostics successfully triggered new developments in the field of mechanical material testing. With the help of a specifically designed, compact and robust spectral domain polarization sensitive OCT (SD-PS-OCT) setup, which is operating at 1.55 μm, dynamic investigations of technical materials - like bulk polymers and composite samples - can be performed under various conditions. Already by evaluating the speckle pattern of the standard SD-OCT images with advanced image processing methods, valuable information on the deformation and flow characteristics of samples subjected to tensile tests can be ...
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  Mentions: Medical University of Vienna Johannes Kepler University of Linz
21. Visualization of microvasculature by dual-beam phase-resolved Doppler optical coherence tomography
  
  Explore opticsinfobase.org Jan 11 2011 Ophthalmology
  
  We present a dual-beam Doppler optical coherence tomography system for visualizing the microvasculature within the retina. The sample arm beams from two identical spectral domain optical coherence tomography (SD-OCT) systems are combined such that there is a small horizontal offset between them at the retina. Thereby we record two tomograms which are slightly separated in time. Phase-resolved Doppler analysis is performed between these two data sets. This system allows blood capillary imaging with high flow sensitivity and variable velocity range. To demonstrate the performance of our system we present images of the microvascular network around the fovea and around the ...
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  Mentions: Medical University of Vienna
22. Dynamic optical studies in materials testing with spectral-domain polarization-sensitive optical coherence tomography
  
  Explore opticsinfobase.org Nov 23 2010 NDE/NDT
  
  By combining dynamic mechanical testing with spectral-domain polarization-sensitive optical coherence tomography (SD-PS-OCT) performed at 1550 nm we are able to directly investigate for the first time changes within scattering technical materials during tensile and fracture tests. Spatially and temporally varying polarization patterns, due to defects and material inhomogeneities, were observed within bulk polymer samples and used to finally obtain – with the help of advanced image processing algorithms – quantitative maps of the evolving internal stress distribution. Furthermore, locally increased stress within fiber-reinforced composite materials was identified in situ with SD-PS-OCT to cause depolarizing sites of fiber-matrix debonding prior the onset of ...
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  Mentions: Medical University of Vienna Johannes Kepler University of Linz
23. Sample motion-insensitive, full-range, complex, spectral-domain optical-coherence tomography
  
  Explore opticsinfobase.org Nov 18 2010
  
  We present a full-range, complex, spectral-domain optical-coherence-tomography (SD-OCT) system that is based on a double-beam scanning approach. The sample beams of two identical SD-OCT setups are combined collinearly by a bulk optic beam splitter before illuminating the object. The required phase shift for the complex signal reconstruction comes from the phase difference between both interferometers. Because of the double-beam scanning approach, our system is completely insensitive to sample motion. To demonstrate the performance of our setup, we present images of the human optic nerve head in vivo and of a human tooth.
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  Mentions: Medical University of Vienna
24. Segmentation and quantification of retinal lesions in age-related macular degeneration using polarization-sensitive optical coherence tomography
  
  Explore SPIE Digital Library Nov 12 2010 Ophthalmology
  
  We present polarization-sensitive optical coherence tomography (PS-OCT) for quantitative assessment of retinal pathologies in age-related macular degeneration (AMD). On the basis of the polarization scrambling characteristics of the retinal pigment epithelium, novel segmentation algorithms were developed that allow one to segment pathologic features such as drusen and atrophic zones in dry AMD as well as to determine their dimensions. Results from measurements in the eyes of AMD patients prove the ability of PS-OCT for quantitative imaging based on the retinal features polarizing properties. Repeatability measurements were performed in retinas diagnosed with drusen and geographic atrophy in order to evaluate the ...
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  Mentions: Medical University of Vienna
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